A number of medically useful compositions comprise two or more ingredients that are not mixed together until shortly prior to use. In some instances, at least one of the ingredients is a solid, usually a powder, whereas at least one of the other ingredients is a liquid in which the solid ingredient is to be dissolved.
Use of a dual-ingredient composition of this kind can be accomplished with a conventional syringe by first loading one ingredient into the syringe, then adding the second ingredient, shaking the syringe or otherwise agitating the contents to achieve effective mixing, and subsequently dispensing the resulting mixture in the usual manner. This procedure, however, presents substantial shortcomings, including possible contamination and loss of sterility. For example, using a conventional syringe of the kind that is filled through a fill needle connected to the outlet orifice of the syringe, it is necessary to replace the needle after the first ingredient has been drawn into the syringe, in order to avoid possible contamination of the supply of the second ingredient. Even then it may be difficult to complete this procedure without rendering the outlet portion of the syringe non-sterile, particularly by extended contact with air.
Another technique that can be employed utilizes a syringe of generally conventional construction in which one ingredient has initially been loaded into the syringe, usually followed by a complete sterilization procedure for the external portion of the syringe. Again, however, it is often rather difficult to load the syringe with the second ingredient without affecting the sterile characteristics of the syringe. Moreover, in both of these procedures the manipulative steps on the part of the user are complex enough that some difficulty may be experienced.
Specialized dual-compartment syringes have been proposed for the administration of two-ingredient medications. For specialized syringes of this kind, reference may be made to Sarnoff et al. U.S. Pat. No. 3,326,215 (incorporated by reference); and Yamada U.S. Patent Application 2004/0064102 A1 (incorporated by reference). However, a dual compartment syringe of this kind is relatively costly and complex in construction, requiring structural members of different configuration from those used in conventional syringes. Moreover, filling a special purpose syringe of this kind can be quite difficult and creates other problems with regard to avoidance of contamination and maintenance of sterility.
In a different approach to this problem, Lindberg, R. M. et al. designed a dual-ingredient dispenser comprising two syringes joined by a releasable connecting sleeve. See Lindberg et al. U.S. Pat. No. 4,060,082 (incorporated by reference). In the Lindberg dispenser, one syringe, used for mixing and dispensing the medication, comprises a housing with inlet and outlet valve-seal members at its opposite ends, and contains a first ingredient in a mixing chamber between the valve-seal members, with the inlet valve-seal member being actuatable from closed to open condition by a fill needle; the other syringe is a carrier syringe filled with a second ingredient and equipped with a fill needle held in alignment with the inlet valve-seal member of the first syringe. Mixture of the material may be achieved by manually shaking the dispenser; however, complete mixing may not occur, especially when forming viscous compositions. In addition, dispensing of the material post-mixing requires the insertion of an additional component into the dispenser.
The known applicator systems are expensive, difficult to sterilize, and/or comprise multiple components, which makes them hard to use. Therefore, there exists a need for an applicator system which is easy to use, can be made sterile, and is inexpensive. Such applicator systems, and methods for their use, are described herein.